The present invention relates to a portable communication device, comprising a plurality of electronic circuits, a battery for supplying power to the circuits, a controller and a memory, the controller being arranged to control the operation of at least some of the circuits by providing control signals, for which the circuits are responsive. The invention also relates to a method of determining power consumption for such a portable communication device.
Users of portable battery-powered communication devices are dependent of a fully functional device. More specifically, the users need to know exactly for how long their devices will remain functional, until the electric energy stored in the battery has been consumed and the battery has to be recharged. This is particularly true for users of mobile telephones. Hence, for the rest of this document a mobile telephone is used, in a non-limiting sense, for exemplifying the inventive portable communication device and method.
In order to determine a precise estimation of the remaining operational time of the mobile telephone, the user needs an accurate and well-functioning battery capacity indicator or xe2x80x9cfuel gaugexe2x80x9d. FIG. 1 illustrates a schematic mobile telephone 1 having a display 6, on which an icon 13 is presented as a battery capacity indicator. As shown in FIG. 1, the battery icon 13 indicates that approximately 25% remains of the initial battery charge. The mobile telephone 1 may have further display facilities for determining and indicating an estimated remaining time of operation, i.e. an estimation of the time left until the battery will have to be recharged.
Determining the remaining battery capacity basically includes two separate current measurements; one measurement for the current flowing into the battery (charging) and one measurement for the current consumed from the battery (discharging).
The charging current is often relatively easy to measure. A microprocessor (CPU) may read an A/D-converted signal, which is directly proportional to the current flowing through a small resistor. Since the microprocessor controls the charging process, it will also have access to all relevant data for calculating the total current, that has been supplied to the battery during a certain period of time.
Measuring the discharge current or current consumption, on the other hand, is much more difficult, particularly for advanced telephones with complex functionality and many operating modes. Traditionally, discharge current is measured by calculating the expected current consumption, when the telephone is in different operating modes. Earlier mobile telephones basically had two operating modes only; talk mode and standby mode. For such mobile telephones, the current consumption in talk mode and standby mode, respectively, was measured once in a test laboratory environment and stored in memory in the telephone as a respective predetermined consumption value. In operation, the telephone would keep track of the time spent in talk mode and in standby mode, respectively, and subsequently calculate the total amount of current consumed from the battery by multiplying the respective operational times with the predetermined consumption values.
Such an approach is disclosed in U.S. Pat. No. 5,248,929, wherein a microprocessor in the mobile telephone regularly executes an interrupt-driven software routine (once every 100 ms), during which the momentary operational mode is determined. The predetermined consumption values are read from memory, and the resulting power consumption value is added to an accumulated value, which in turn is used for determining remaining battery capacity and operational time in talk mode and standby mode.
Although providing an acceptable power consumption estimation for a simplified scenario with only two operating modes, the prior art approach described above has not proven applicable to more advanced telephones having a plurality of operational modes. For instance, the power consumption of a contemporary TDMA (xe2x80x9cTime Division Multiple Accessxe2x80x9d) telephone does not only depend of whether the telephone is in standby mode or talk mode; the power consumption is affected by at least the following conditions in standby mode and talk mode, respectively:
Standby Mode
Number of neighboring base stations
Paging frequency
Backlight
LCD icon mode on/off
Location update frequency
Top indicator
Accessory connected/disconnected
Talk Mode
Output power
Backlight
Band (900/1800/1900 MHz)
HR/FR/EFR (Half Rate/Full Rate/Enhanced Full Rate), i.e. speech encoder mode
HF algorithm
DTX/no DTX (Data Transmission)
DRX/no DRX (Data Reception)
Accessory connected/disconnected
A very large number of different operating modes may originate from various combinations of individual conditions above, and consequently there is an urgent need for an alternative way, other than the one described above, of determining battery power consumption.
The object of the present invention is to provide a new and substantially improved way of determining battery power consumption for a portable communication device, such as a mobile telephone.
Generally, the object has been achieved by the inventive realization that for any communication device, the different electronic circuits of which are controlled by submitting control signals from a central controller (such a microprocessor or CPU), prestored power consumption values for individual circuits may be predetermined and subsequently used by the controller for counting the occurrence of different control signals and calculating a total power consumption from the results of the count and the predetermined individual consumption values.
The invention is particularly well adapted for a TDMA telephone, which uses different control pulses or xe2x80x9cstrobesxe2x80x9d for switching on and off different radio circuits, e.g. power amplifier, filters and synthesizer, as well as other electronic circuits, e.g. D/A converters. The strobes are all completely controlled by the microprocessor in such a way, that the telephone may send and receive in the correct timeslot.
More specifically, the object above has been achieved by a portable communication device and a method of determining the power consumption thereof according to the appended independent patent claims. Other objects, features and advantages of the present invention will appear from the following detailed disclosure, from the attached drawings as well as from the dependent claims.